Control surfaces are used on aircraft to influence the passage of fluid over various flight surfaces such as wings. By “control surfaces” we mean movable components that produce an aerodynamic effect for example flaps, slats, ailerons and spoilers. Flaps, for example, are a type of control surface which are mounted to the rear of a wing and can be rotated with respect to the wing trailing edge to change the shape of the aerofoil profile of the wing assembly as a whole. This helps prevent wing stall at low speeds (e.g. during landing) when the flaps are fully deployed, and increases efficiency of the wing at high speeds (e.g. during cruise) when the flaps are stowed.
Control surfaces such as flaps need to be securely mounted to the aircraft. Flaps can be mounted to the wings of the aircraft in a variety of ways, for example via an underslung beam attached to the underside of the aircraft wing, or via a cantilever rib mounted directly to, and projecting perpendicularly from, a rear spar of the wing.
Both of these methods require that the beam or rib project from the outer mean line (OML) of the wing due to the fact that the desired pivot axis of the flap is below the OML. As such, the beam or rib will necessarily project into the fluid stream across the flight/control surfaces. This increases drag and hence reduces the efficiency of the aircraft which is undesirable.
In addition such beams or ribs need to be large enough to provide a load path from the flap to the wing as well as house actuators for deployment of the flap. As such they are often large.
The problem of control surface structure drag is particularly prevalent in large fixed wing aircraft in which the wings are swept to increase aerodynamic efficiency. The trailing edge of the wing, is non-perpendicular to the line of flight, and hence the direction of flap deployment is also non-perpendicular to the line of flight (rather it is parallel to the trailing edge of the wing). The beam or rib is mounted perpendicularly to both the trailing edge of the wing (i.e. the rear spar) and the leading edge of the flap. Specifically, it spans the shortest distance between them.
This is problematic as the beam or rib is non-parallel to the line of flight in swept wings. As such the “footprint” of the beam or rib viewed in the direction of the line of flight is relatively large due to its orientation. This further increases the effects of drag on the beam or rib.
It is known to cover these components in an aerodynamic fairing to reduce the drag produced, however this cannot completely eliminate it.
It is an object of the present invention to provide an improved mounting structure.